Source : Webster's Revised Unabridged Dictionary (1913)

Cyanosis \Cy`a*no"sis\ (s?`?-n?"s?s), n. [NL. See {Cyanic}.]
   (Med.)
   A condition in which, from insufficient a[eum]ration of the
   blood, the surface of the body becomes blue. See
   {Cyanopathy}.

Source : WordNet®

cyanosis
     n : a bluish discoloration of the skin and mucous membranes; a
         sign that oxygen in the blood is dangerously diminished
         (as in carbon monoxide poisoning)